Blu-ray fits the bill for infrequently accessed data, Facebook said

If you thought Netflix and iTunes would make optical discs a thing of the past, think again. Facebook has built a storage system from 10,000 Blu-ray discs that holds a petabyte of data and is highly energy-efficient, the company said Tuesday.

Facebook said last year that it was exploring Blu-ray for its data-center storage needs, and on Tuesday it showed a prototype system at the Open Compute Project summit meeting in San Jose, California.

It designed the system to store data that hardly ever needs to be accessed, or for so-called "cold storage." That includes duplicates of its users' photos and videos that Facebook keeps for backup purposes, and which it essentially wants to file away and forget.

The Blu-ray system reduces costs by 50 percent and energy use by 80 percent compared with its current cold-storage system, which uses hard disk drives, said Jay Parikh, Facebook's vice president of infrastructure engineering, in a talk at the Open Compute summit.

The company expects to be able to increase the capacity of the system to five petabytes over time, he said.

Blu-ray discs are a good option for cold storage because they cost less to buy than hard disks and there's a lot of room for manufacturers to increase the storage density of Blu-ray, said Jason Taylor, Facebook's director of infrastructure, in an interview.

If the idea takes off, it might extend the life of the optical disc industry.

"We see this as a new area of demand for the technology," Taylor said.

The machine Facebook built is still a prototype, but it expects to start production tests later this year, he said.

Parikh showed the system on stage at the Open Compute summit. Outside it looks like a plain server cabinet, about 7 feet tall, but inside there's all kinds of robotic wizardry to move the discs around.

The discs are stacked in piles, and a robotic picker can quickly select a disc from a pile and move it to one of 16 burners in the system, which write data to the discs.

Facebook is still deciding which parts of the design it will submit to Open Compute Project, Taylor said.

The social network set up the Open Compute Project about three years ago as a way for it to collaborate with peers to develop hardware that better suits their needs.